1. Field of the Invention
This invention relates to compositions comprising nickel (II) thiobis(alkylphenolates) complexed with hydroxyl-substituted ligands and polyolefinic polymers. Said compositions contain a minor amount of said nickel thiobis(alkylphenolate) complex sufficient to impart antioxidant and ultra-violet stabilization thereto and a major amount of said polyolefinic polymers. Polyolefin plastic compositions normally require the presence of stabilizing agents to inhibit oxidative degradation catalyzed inter alia by ultra-violet and/or visible light, or other high energy conditions.
2. Description of the Prior Art
Commercially available ultra-violet stabilizers are listed by class and function and identified as to structure in the Kirk-Othmer Encyclopedia in "Encyclopedia of Chemical Technology"; Second Edition, Vol. 21, pp. 115-122. U.S. Pat. No. 3,832,304 discloses the use of aromatic azo compounds for stabilizing hydrocracked oils. U.S. Pat. Nos. 2,703,786; 2,716,090 and 3,210,277 disclose the use of polyvalent metal, e.g., Ni salts of thiobis(alkylphenols) as oxidation inhibitors and plasticizing agents. Nickel thiobis-(4-t-octylphenolate) is disclosed in U.S. Pat. No. 2,971,940 as a stabilizer for plastics, and complexes thereof with amines, e.g., n-butylamine are disclosed in U.S. Pat. No. 3,215,717 as a plastic stabilizer. However, none of the foregoing disclosures are directed to compositions containing the organosulfur-nickel complexes described in accordance with this invention. Further, the subject complexes with hydroxy-substituted ligands are not disclosed by any prior art known to applicant. Accordingly, their use in plastics to impart resistance to oxidative and other similarly induced degradation is also believed to be novel. The complexes in accordance herewith in combination with co-antioxidants such as hindered phenols show an even more remarkable degree of improvement in controlling oxidative degradation. Also useful as co-antioxidants are diarylamines and phenothiazines.